1. Field of the Invention
This application relates in general to a thermomagnetic generator and in particular to a thermomagnetic generator applying hot and cold liquids.
2. Description of the Related Art
Thermomagnetic generators are devices that convert heat into electrical energy. They utilize the magnetic and magneto-caloric properties of magneto-caloric material which changes rapidly with temperature near a magnetic phase transition temperature, such as a Curie temperature. The magneto-caloric material is conventionally provided in a magnetic circuit. A coil or resonant circuit may be provided near the magnetic circuit for obtaining an induced voltage.
A temperature-varying device is usually provided in the thermomagnetic generator for varying the temperature of the magneto-caloric material. The temperature-varying device may apply hot and cold liquids through individual pipes to change the temperature of the magneto-caloric material above and below the magnetic phase transition temperature. The rapid variation of temperature above and below the magnetic phase transition temperature can magnetize or demagnetize the magneto-caloric material, so as to change the magnetic resistance (reluctance) of the magnetic circuit. Thus, an electrical voltage can be induced through the coil in response to the variation of the magnetic circuit. A typical configuration of a thermomagnetic generator can be found in the prior art of Solomon, Dan, “Improving the performance of a thermomagnetic generator by cycling the magnetic field”, Journal of Applied Physics, volume 63, issue 3, pp. 915-921 (1988).
In conventional thermomagnetic generators, the hot and cold liquids are individually controlled by switch valves. When one pipe is opened to the magnetic circuit, the other pipe is closed. Thus, since the hot and cold liquids can not be continuously and simultaneously used, utility of the liquid and efficiency of the thermomagnetic generator is low.